Then I’m going to go to the post office and buy stamps.
That foreigner bought 10,000 postage stamps.
Since I lost her, I've lost interest in stamp collecting.
To remember the meaning of this word, just think about how in the olden days, before perforation was invented, people had to cut their postage stamps by hand. It took forever, especially if you had a lot of friends to mail things to. Be thankful that perforation was invented to save you time cutting them.
You'd think that the reading for this would consist of the on'yomi readings, but human body parts (hand) do funny things to words. In this case, it's the kun'yomi readings of both the kanji. You should know the kun'yomi reading for 切 and 手 from the previous levels, meaning you should be able to remember the reading for this word fairly easily. Watch out for the small っ, though.